pub struct SameLayer {}

impl SameLayer {
    pub fn new() -> SameLayer {
        return SameLayer {};
    }

    pub fn set(&mut self, _key: String, _value: String) {}

    pub fn get(&mut self, _key: &String) -> String {
        return "".to_string();
    }
}

#[cfg(test)]
mod tests {

    use super::*;

    fn test_1() {
        let mut b = SameLayer::new();
        b.set(String::from("main.rs同级key"), String::from("main.rs同级value"));
        // main.rs里有mod same_layer时，警告get()没被使用？？;
        // expected value, found struct `String`??? {:?} -> 报错就在main.rs里把mod same_layer;去掉
        println!("b:\n{}", b.get(String.from("main.rs同级key")));
    }

}